The overarching goal of this study is to establish a large offspring cohort to investigate the long-term intergenerational impacts of GDM and obesity on the metabolic, vascular, and reproductive health of the offspring. In the present study, we will apply a hybrid design which combines maternal and offspring data that have been prospectively with new biomarker data. This study will leverage two ongoing mother-offspring cohorts, the Nurses Health Study II (NHS-II; mothers) and the Growing Up Today Study (GUTS; offspring) in the United States (herein referred to as the Harvard School of Public Health, HSPH, site) and the mother-offspring pairs in the Danish National Birth Cohort (DNBC) in Denmark collected over more than 20 years and covering a lifespan from pre-conception through young adulthood. The study is in the process of biospecimen analysis of markers of metabolic and reproductive function.